Textual: Verses 18-20 are directly from Isaiah:
Isaiah 52:8-10
8 Thy watchmen shall lift up the voice; with the voice together shall they sing: for they shall see eye to eye, when the LORD shall bring again Zion.
9 Break forth into joy, sing together, ye waste places of Jerusalem: for the LORD hath comforted his people, he hath redeemed Jerusalem.
10 The LORD hath made bare his holy arm in the eyes of all the nations; and all the ends of the earth shall see the salvation of our God.
The conclusion of this instruction to the twelve underlines the eschatological reference of the ultimate redemption of Israel. It is in this greater context that we can understand the otherwise unattached verse 16 that reiterates the promised land of the Nephites. This discourse that is directed specifically to the twelve comes at the end of the Sermon on the Mount, and comprises part of our current chapter 15 and all of 16. This discourse begins with issues of separation, and ends with issues of unification. Our current verse 16 here is a reiteration that the current role of the New World twelve is still one of separation, but that what they write will play an important role in the final unification of the currently divided Israel.
This is the end of a chapter in the 1830 edition.